Soybean (Glycine max L. Men) is a major cash crop and investment commodity in North America and elsewhere. Soybean oil is one of the most widely used edible oils, and soybeans are used worldwide both in animal feed and in human food production. Sensitivity to the herbicide metribuzin in soybeans is a widespread problem in the United States. Metribuzin is a photosystem II inhibitor. It is useful for control of weeds which have become resistant to herbicides with different modes of action such as PPO inhibitors. The main limitation to the use of metribuzin is that some soybean varieties are more sensitive than others (Wax et al. Agron. Journal. 68:484-486, 1976). The symptoms of metribuzin sensitivity include leaf phytotoxicity.
Different varieties of soybean vary in their sensitivity or tolerance to metribuzin. Therefore, one of the most effective control measures is planting metribuzin tolerant soybean varieties. Currently, determining whether a soybean cultivar might have tolerance to metribuzin typically involves testing each cultivar in the field or greenhouse under conditions that typically produce a phytotoxicity reaction in metribuzin sensitive plants. Thus, the present invention overcomes the shortcomings in the art by providing markers associated with tolerance to metribuzin thereby allowing the characterization of soybean cultivars for metribuzin tolerance by molecular analysis rather than phenotypic analysis.